Don't send the body of the redirected request to the ServiceWorker.

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/navigation-redirect-body-worker.js

+self.addEventListener('fetch', function(event) {
+    event.respondWith(
+        fetch(event.request)
+          .then(
+              function(response) {
+                return response;
+              },
+              function(error) {
+                return new Response('Error:' + error);
+              }));
+  });